MIT Press has just published Philip R. Zimmerman's "PGP Source Code and Internals", a 900+ page tome containing:
As the Preface explains, cryptographic software is classed as a munition, subject to export restriction by the U.S. State Department. Except that there appears to be an exception for software that is printed on paper, rather than written on "computer-readable" media.
I'm not making this up! Bruce Schneier's fine exposition, "Applied Cryptography", can be exported without problems, despite the fact that it contains hundreds of pages of source code. Floppy disks containing the same code, in contrast, may not be exported from the U.S.
So, this new book is really a way of testing the limits of U.S. law. As the Preface says: It will be interesting to see where this process leads.